Electronically controlled stitching machine

ABSTRACT

A STITCHING MACHINE IS DISCLOSED WHICH INCLUDES FIRST MEANS IN THE FORM OF A STITCHING HEAD FOR APPLYING STITCHES TO A WORK PIECE PASSING THEREBY, SECOND MEANS PREFERABLY IN THE FORM OF COOPERATING PULL ROLLERS FOR CONVEYING THE WORK PIECE PAST THE STITCHING HEAD, A MOTOR SELECTIVELY CONNECTABLE TO THE PULL ROLLERS FOR THE OPERATION THEREOF, INTERCONNECTION MEANS IN THE FORM OF A CLUTCH-BRAKE COMBINATION RESPONSIVE TO PRESELECTED OPERATING SIGNALS FOR SELECTIVELY CONNECTING AND DISCONNECTING THE MOTOR TO THE PULL ROLLERS TO THEREBY EFFECTUATE INCREMENTAL INDEXING OF THE WORK PIECE PAST THE STITCHING HEAD, AND ELECTRONIC CONTROL MEANS FOR GENERATING THE PRESELECTED OPERATING SIGNALS NECESSARY TO EFFECTUATE THE INCREMENTAL ADVANCE OF THE WORK PIECE THROUGH THE MACHINE. IN A PREFERRED EMBODIMENT, THE ELECTRONIC CONTROL MEANS IS RESPONSIVE TO THE OPERATION OF THE STITCHING HEAD AND INCLUDES CIRCUITRY DESIGNED TO PRODUCE AN EXTREMELY RAPID ENERGIZATION AND DE-ENERGIZATION OF THE CLUTCH BRAKE COMBINATION DEFINING THE AFOREMENTIONED INTERCONNECTION MEANS WHEREBY EXTREMELY ACCURATE HIGH-SPEED STITCHING IS MADE POSSIBLE.

May 23, 1972 5 G ET AL 3,664,564

ELECTRONIUMJLIY CONTROLLED S l'l'lClH Nki MACH I NH Filed Sept. 16, 1970 3 Sheuts-$heot 1 UL I lN"FNTORS-' STEPHEN STANTON Y EDWARD VARHOLY LERNER, DAVID 8| L/TTENBERG ATTORNEYS May 23, 1972 s. STANTON ETAL ELECTRONICALLY CONTROLLED SFI'I'CHING MACHINE 3 Sheets-Sheet 2 W58 MOTOR u 6 I m w m .P A 0 m J m 0 w I M 8 I? Mm m 6 2 h I I W 5 A :II J 4 2 I m M HQ 4 P 6 1W4 B W l w awn a A O V I 2 m u 2 H 2 1 H m BRAKE ON CLUTCH ON May 23, 1972 '5, STANTON ETAL 3,664,564

ELECTRONICALLY CONTROLLED STITCHING MACHINE} IIO- CLUTCH ON BRAKE ON V 60ms I I 40ms lms Ims FIG. 6

United States Patent 3,664,564 Patented May 23, 1972 3,664,564 ELECTRONICALLY CONTROLLED STITCHING MACHINE Stephen Stanton, Baltimore, and Edward Varholy, Glen Burme, Md., assignors to Flynn & Enrich Company,

Baltimore, Md.

Filed Sept. 16, 1970, Ser. No. 72,764 Int. Cl. B27f 7/06 US. Cl. 227-100 18 Claims ABSTRACT OF THE DISCLOSURE A stitching machine is disclosed which includes first means in the form of a stitching head for applying stitches to a work piece passing thereby; second means preferably in the form of cooperating pull rollers for conveying the work piece past the stitching head; a motor selectively connectable to the pull rollers for the operation thereof; interconnection means in the form of a clutch-brake combination responsive to preselected operating signals for selectively connecting and disconnecting the motor to the pull rollers to thereby effectuate incremental indexing of the work piece past the stitching head; and electronic control means for generating the preselected operating signals necessary to effectuate the incremental advance of the Work piece through the machine. In a preferred embodiment, the electronic control means is responsive to the operation of the stitching head and includes circuitry designed to produce an extremely rapid energization and de-energi-zation of the clutch brake combination defining the aforementioned interconnection means whereby extremely accurate high-speed stitching is made possible.

BACKGROUND OF THE INVENTION This invention relates to box stitching machinery or apparatus, and more particularly to such box stitching machinery which operates on the principle of incremental advancement of the work piece therethrough.

In the art of box stitching, it has been known for many years to construct a box stitching machine comprising a stitching head for applying wire stitches to the overlapping portions of a box blank passing therebeneath, and conveying means for incrementally advancing the box blank passed the stitching head. Conventionally, such conveying means has taken the form of cooperating pull rollers which sandwich the box blank therebetween and advance same through the machine in response to the driving rotation thereof.

In the control of such machinery, at start up it is necessary to have the pull rolls operating at a continuous high rate of speed to initially convey the box blank from the input side of the machine (and normally from the operators manual control of the box blank) toward the stitching station defined by the stitching head. When the box blank has reached a preselected position with respect to the stitching head, appropriate sensing means (in the form of a mechanical sensing finger or a photocell arrangement) detects the leading edge of the box blank to energize a timer which after timed out, generates a command signal to start the operation of the stitching head which then begins to apply the first stitch to the box blank now positioned therebeneath.

Simultaneously, a signal must be generated to stop the aforementioned pull rollers such that the box blank will .be stationary beneath the head when the first stitch is applied thereto. After the completion of the first stitch, and after the stitch driving means associated with the head has been lifted from the box blank, another signal must be generated to start the pull rollers moving again to advance the blank a preselected distance whereupon the pull rollers must again be stopped to halt the movement of the box blank to await the application of the next stitch being applied by the now continuously operating stitching head. This cycle of stop and start movement of the box blank, and the application of a stitch at the stop or dwell period of the box blank motion, continues until a preselected number of stitches have been applied. At that point, the stitching head must be de-energized, and the pull rolls retuned to their earlier mode of continuous operation to rapidly eject the box blank out the rear of the stitching machine.

In the prior art stitching machines over which the instant invention is intended to be an improvement, all of the above control signals are generated by purely mechanical means. For example, prior art apparatus of the type in question employ cams, cam followers, mechanical gear trains, etc., to generate, synchronize, and coordinate the various operations discussed above. Typical of this type of operation is the box stitching apparatus disclosed for example in US. Patent 2,785,403. It will be appreciated however, that in addition to being relatively complex and expensive to manufacture, such mechanically controlled mechanisms are extremely slow. In fact, the slow stitching speed which necessarily results from this type of mechanical operation is one of the prime reasons that box stitching apparatus of this type incorporating wire stitching heads are not readily accepted in the box forming industry.

Specifically, when given a choice, box manufacturers would rather employ tape dispensing and/ or gluing machinery to fabricate cardboard boxes. This is so since such machinery can be operated in a continuous mode (that is the tape or glue being applied to the moving box blank) as compared to the incremental advancement (stop and start motion) utilized in wire stitching apparatus. However, for boxes designed for extremely heavy contents, tape and/or glue is not a sufficient joining means, and the fabricators must turn to wire stitches to provide the necessary strength.

However, and for the reasons discussed above, such wire stitching machines operate at such a slow rate of speed that fabricators have been faced with a choice involving the best of two evils: either they can refrain from manufacturing wire joined cartons (and lose the potential business income derived therefrom), or they incur great operating expenses by either shutting down, slowing down, or losing time on their high speed tape and/0r glue production lines in favor of manufacturing the wire joined boxes on the much slower wire stitching apparatus. This problem becomes especially severe in situations for example where the customer desired a wire stitched carton (for strength), but also requires tape and/ or glue on the box seam, for example, to make it impervious to water. In that situation, the boxes which have been taped and/or glued on the main high-speed production line must be slowed down to receive the wire stitches or physically removed from the production line to another location where the wire stitching apparatus is employed.

Equally as important, if not more so, is the problems relating to poor stitching accuracy which results from the above described mechanically controlled box stitching apparatus. Specifically, it is one of the basic requirements of box stitching apparatus that the stitches be applied at precisely desired locations (for example with respect to the leading and trailing folds which define the intermediate body portion of the planar box blank). Similarly, it is essential that the spacing between adjacent stitches be maintained uniform throughout a given stitching sequence. However, with box stitching apparatus employing me- 3 chanical means to synchronize and control the operation thereof, extended usage over long periods of time necessarily results in mechanical wear, looseness or play, etc., all of which has the unstoppable effect of completely destroying the close tolerances which are essential in the industry.

SUMMARY OF THE INVENTION In contradistinction to the prior art, the instant invention provides wire stitching apparatus broadly similar to the above described wire stitching apparatus but which employs high speed electronics to control, synchronize and assure the necessary cooperation of the various components thereof.

More specifically, wire stitching machinery constructed in accordance with the teachings of the instant invention broadly includes a stitching head for applying fastening means (in the form of wire stitches) to a work piece (the box blank) passing thereby; second means (preferably in the form of pull rollers) for conveying the work piece past the stitching head; motive means (in the form of an electric motor) selectively connectable to the pull rollers for the operation thereof; interconnection means (in the form of a clutch and brake) responsive to preselected operating signals for selectively connecting and disconmeeting the electric motor to the pull rollers to thereby control the incremental stop and start operation thereof; and electronic control means for generating the preselected operating signals necessary to properly control and synchronize the clutch and brake defining the aforementioned interconnection means. Preferably the electronic control means is responsive to the operation of the stitching head but, it is within the purview of this invention that both the stitching head and the electronic control means could be operated by and synchronized by a central programmer.

In the broad application of the instant invention, the aforementioned clutch and brake may be of conventional construction operating on mechanical principles and energized upon the application of electrical signals to operating solenoids the movement of whose armatures is indirectly used to engage and disengage the mechanical clutch and brake. In this context, the electronic control means of the instant invention and its relationship to the operation of the stiching head will guarantee the quick and highly accurate generation of the operating signals utilized to energize the respective operating solenoids. In this manner, the stitching machine will be significantly faster than its equivalent counterpart in the prior art and, equally as important, significantly more accurate.

In various preferred embodiments of the instant invention, the inventor has chosen to employ what may be conveniently classified as purely electrical clutches and brakes in the sense that an electrical signal applied thereto is directly utilized to bring about the engagement of the respective device. For example, typical of this type of clutch or brake is a device which includes a coil located directly in one of the two confronting pieces which define the clutch or brake. When an electrical signal is applied to such coil, a magnetic path is established through both halves of the clutch or brake to physically draw the movable portion thereof into engagement with the nonmovable portion thereof. With such purely electrical devices, however, the physical mass of the movable half dictates the utilization of an extremely high voltage to bring about the initial engagement of the confronting parts. Once engaged however, with the moving mass requiring no further lateral movement, a much smaller voltage can be used to maintain the clutch or brake engagement.

In accordance with a further aspect of the invention, the electronic control means thereof includes means to generate an extremely high voltage spike during an initial portion of the preselected period during which the clutch or brake is to remain engaged, and means for applying the lesser required operating voltage to the clutch or brake for the remaining portion of the preselected period of time during which the clutch or brake is to remain engaged. In this manner the spike insures the rapid engage ment of the clutch and brake of the interconnection means, thereby increasing the speed of operation of the machine and simultaneously guaranteeing the accuracy of the interstitch spacing required.

Accordingly, it is an object of the instant invention to provide a stitching machine comprising first means for applying fastening means to a work piece passing thereby; second means for conveying said work piece passed said first means; motive means selectively connectable to said second means for the operation thereof; interconnection means responsive to preselected operating signals for selectively connecting and disconnecting said motive means and said second means; and control means for generating said preselected operating signals.

Another object of the instant invention is to provide such a Stitching machine which controls, synchronizes and assures the cooperating of the various components thereof by means of high speed electronics.

Yet another object of the instant invention is to provide such a stitching machine which is materially faster and more accurate than the stitching machines available in the prior art.

These as well as other objects of the instant invention will be had by referring to the following description and drawings in which:

FIG. 1 is a somewhat schematic pictorial illustration of a wire stitching machine constructed in accordance with the teachings of the instant invention;

FIG. 2 is a side view, partly in section, of a portion of the wire stitching machine illustrated in FIG. 1;

FIG. 3 is a schematic circuit diagram of the control means of the instant invention illustrating the manner in which it cooperates with the stitching head and conveying system thereof;

FIG. 4 is a graph illustrating the cycle of operation of the clutch and brake schematically illustrated in FIG. 3;

FIG. 5 is a schematic circuit diagram illustrating the manner in which an alternative embodiment of the electronic control means of the instant invention cooperates with an alternative embodiment of a clutch and brake which can be employed therein; and

FIG. 6 is a graph illustrating the cycle of operation of the clutch and brake illustrated in FIG. 5.

Turning to the figures wherein like numerals are used to designate like elements, there is shown the wire stitching machine 10 of the instant invention. Broadly speaking, and as will be described in greater detail, the machine 10 includes first means 12 for applying fastening means to a work piece 14 incrementally passing therebeneath on a work table 13. Second means broadly designated 16 are provided for conveying the work piece 14 passed the first means 12. Motive means 18 are provided, and as will be described, are selectively connectable to the second means 16 for the driving operation thereof. Interconnection means 20 are responsive to preselected operating signals to selectively connect and disconnect the motive means 18 to the second means 16. Finally control means 22 (FIG. 2) are provided for generating the necessary operating signals for the interconnection means 20. Preferably the control means 22 is responsive to the operation of the first means 12, but it is within the purview of the invention that both the control means 22 and the first means 12 could be operated by and Synchronized by a central programmer (not shown).

In the wire stitching machine of the instant invention, the first means 12 takes the form of a wire stitching head which, when energized, applies wire stitches to the work piece 14 passing therebeneath. In the system of the instant invention, the Wire stitching head 12 may be any conventional, well known stitching head available in the industry, but most preferably, takes the form of the wire stitching head disclosed and claimed in US. patent application Ser. No. 37,190, filed May 14, 1970, in the name of Lauri C. Barland entitled Stitching Head Apparatus and assigned to the assignee of the present invention.

In order to understand the manner in which the stitching head 12 functions within the overall stitching machine of the instant invention, and to point out the manner in which any other stitching head might be modified to function in the machine 10 of the instant invention, it is initially worthwhile perhaps to outline the operation of the stitching head 12 which in the drawings, takes the form of the head disclosed in the aforementioned application Ser. No. 37,190.

The stitching head 12 includes on a front face 24 thereof vertically reciprocating stitch forming and driving means broadly designated 26. As explained in greater detail in the aforementioned application, the stitch forming and driving means 26 is vertically reciprocally driven, when the stitching head is operating, by a pair of links 28 and 30 pivotally secured to a driving cam 32. As explained in the Barland application, when the driving cam 32 is rotated, a stitch is fed, cut, formed and driven into the work piece positioned beneath the head, with the forming and driving means 26 actually coming into contact with the work piece for a small portion of the overall stitch forming and driving cycle.

The cam 32 is secured on one end of a shaft 34 the rear end 36 of which passes out the rear of the frame 38 of the head 12. Motion is imparted to the shaft 34 by a continuously running electric motor 40 the output shaft 42 of which is applied to a gear train 44, 46, and a clutch 48 selectively energizable to interconnect the continuously rotating gear 46 to the shaft 34. As explained in the Barland application, the clutch 48 may be engaged or disengaged by the selective energization of a clutch coil 50 which when energized moves a lever 52 to engage the clutch and thereby impart rotary motion to the shaft 34 and the driving cam 32.

Positioned adjacent the rear end 36 of the shaft 34 of the head 12 is a pair of normally open contacts 54 which are maintained closed whenever the normal uninterrupted circumference or periphery 56 of the end of the shaft 36 is in engagement and maintained thereagainst. However, the rear end of the shaft 34 also includes a fiat cordal segment 58 which when confronting the contacts 54 will allow the contacts to revert to their normally open condition for purposes to be described below.

It should be pointed out, that the size of the cordal 1 flat 58 and its location with respect to the contacts 54 are chosen such that during the stitching operation, it is only when the stitch forming and driving means 26 is actually driving the stitch into the Work piece 14 that the cordal segment 58 confronts the contacts 54. At all other times during the stitching cycle, that is, when the stitch forming and driving means 26 is experiencing up and down motion (but not actually driving the stitch), the uninterrupted peripheral surface 56 of the shaft 34 confronts and maintains the contacts 54 in their closed condition. As will be explained below, it is the opening and closing of these contacts 54 which synchronize the operation of the stitching head 12 with the stop and start motion of the second means 16 which conveys the work piece past the stitching head 12.

A second pair of contacts 60 are provided in close proximity to the path of motion of the stitch forming and driving means 26. Each time the stitch forming and driving means 26 rises to complete the application of a stitch, the contacts 60 are closed, and as will be explained below, a counter is advanced to accumulate the number of stitches being applied in any given stitching sequence. It will be appreciated that the contacts 60 are shown schematically in FIGS. 1 and 3. Any type of contacts may be used including a magnetic reed switch operable by a magnetic member secured to and movable with the vane of the stitching head. After a preset number of stitches have been applied, the clutch coil 50 will be deenergized, to disengage the clutch; the stitching operation will cease; and the control system 22 will generate appropriate signals to cause the second means 16 to revert from its stop and start operation to its continuous mode of operation to eject the work piece 14 from the stitching machine 10.

Thus it will be appreciated from the brief description presented above, that to function in the stitching machine 10 of the instant invention, the stitching head 12 employed must really include only three basic components. There must be some means (such as the clutch coil 50) to begin and stop its operation; there must be some operating means (such as the contacts 54 cooperating with the shaft end 36) to generate signals indicative of the portion of the overall stitching cycle that the stitch forming and driving means is driving a stitch into the work piece 14; and third means (such -as contacts 60) for generating a count of the number of stitches driven in a particular sequence. Thus it will be appreciated that these three basic operating characteristics could be derived from an appropriately modified conventional stitching head available in the industry, and it was on this basis that such comment was made earlier in the description.

Returning to the overall stitching operation, the work piece 14 is, in the system of the instant invention, a cardboard box blank which has been appropriately folded to include overlapping side edges 62 and 64 which are to be joined by the wire stitches applied by the stitching head 12. In this connection, a conventional guide shoe 66 is provided with oppositely directed receiving pockets to properly align the overlapping edges 62 and 64 as they enter the machine 10.

The second means 16 for conveying the work piece 14 past the stitching head 12 comprises cooperating pairs of pull rollers 68, 70, 72 and 74 fixedly secured on shafts 76 and 78. In the disclosed embodiment, shaft 78 is an idler shaft while shaft 76 is driven through universal coupling 80 and the motive means 18 upon the selective energization and de-energization of the interconnection means 20 to be described below. It will be appreciated that when the motive means 18 is connected to the shaft 76 by way of the interconnection means 20; the driving rollers 68 and 72 in conjunction with the rollers 70 and 74 will advance the work piece 14 through the machine 10 and under the stitching head 12.

The motive means 18 preferably takes the form of a continuously operating electric motor the speed of which can be preset by the machine operator. As will be ap parent below, the speed chosen for the motor 18 determines the spacing between stitches.

The interconnection means 20 takes the form of a clutch 82 and a brake 84. As briefly mentioned above, in various embodiments of the instant invention the clutch 82 and brake 84 may be of the electromechanical type (in the sense that they depend upon the electrical energization of a coil to generate mechanical motion used in turn to engage and disengage a purely mechanical clutch); or the clutch 82 and brake 84 may comprise what has been designated a purely electrical device in the sense that the flux path established by the energizing coil thereof is directly utilized to engage the clutch or brake respectively.

Finally, the control means 22 shown in detail in FIGS. 3 and 5 are utilized to perform the following operations. Initially, when the stitching machine 10 is first turned on, the electric motor such as 40 associated with the stitching head and the electric motor 18 of the motive means are running. At this point, the control means 22 must generate an operating signal which guarantees that the clutch 82 is on and the brake 84 is 01f, such that the motor 18 is connected to the drive shaft 76. In this manner, the pull rollers 68 and 72 are continuously running at a high rate of speed awaiting the reception of the first work piece 14. The operator then places the first work piece 14 in its proper relationship with respect to the guide shoe 66 and pushes it into the grasp of the pull rollers. Thus the work piece will be taken over from the operator and rapidly advanced toward the stitching head 12.

Subsequently, when, in a manner to be further described, the work piece reaches a predetermined location with respect to the stitching head, and the stitching head initiates a stitch forming and driving operation; the control means is utilized to quickly generate an operating signal which energizes the brake 84 and de-energizes the clutch 82 thereby quickly stopping the work piece for that brief period of time necessary for the work piece to receive the stitch from the stitching head. Immediately thereafter, when the stitch forming and driving means of the stitching head '12 has been withdrawn from the work piece, the control means must quickly generate another operating signal to turn on the clutch 82 and de-energize the brake 84 to thereby start the pull rollers and the work piece moving again.

In the short interval of time that the work piece is advancing, the stitching head has completed a full cycle and is ready to deposit the next stitch into the work piece. Thus the control means 22 must again rapidly apply an operating signal to energize the brake 84 and de-energize the clutch 82 to make sure that the Work piece is again at rest and at a dwell period when the next stitch is applied by the stitching head 12. This sequence continues until a preselected number of stitches (dependent upon the size of the work piece) has been driven at which time the stitching head is de-energized, and the control means must be capable of maintaining an operating signal on the clutch to revert the pull rolls to their continuous mode of motion and thereby eject the work piece out of the rear of the machine.

From the above description, it can be appreciated why the control means utilized to synchronize the operation of the stitching machine of the instant invention must be extremely quick acting and reliable. To emphasize this point, it should be appreciated that in stitching machines of the type under consideration, it is desirable that the stitching head be capable of applying more than 600 stitches per minute to the work piece incrementally advancing therebeneath. Quite clearly then, the importance of the synchronizing control means cannot be over estimated. It should be equally as clear, that the mechanical controls prevalent in the prior art simply cannot function accurately at the high rates of speed involved.

Turning to FIG. 3, there is illustrated in detail, one embodiment of the control means 22 and the manner in which it cooperates in an overall wire stitching machine of the instant invention. In this embodiment of the invention, the clutch 82' and the brake 84 are of the electro-mechanical type in the sense that energization of their respective operating coils 86 and 88 are utilized to displace an armature 90 and 92 respectively which in turn engages or disengages the clutch 82' or brake 84 constructed of and operating upon conventional mechanical principals. In this connection, it might be pointed out that the clutch 82' is schematically illustrated in FIG. 3 for the reason that any available mechanical clutch suitable for the operating characteristics desired may be employed. For example, one might employ the type of clutch described in detail in the aforementioned application Ser. No. 37,190, but in a broader sense any convenient clutching mechanism can be employed. Similarly, the brake 84' is schematically shown to suggest that any convenient braking apparatus available in the industry can be employed. For example, the brake 84 could comprise an oppositely operated clutch arranged to halt the rotation of one of the shafts thereto upon proper energization, and permit free rotation there of upon its de-energization. *Of course, any other equivalent braking apparatus can be interchangeably employed as Well.

As noted previously, when the stitching machine 10 is turned on, pull rollers 68 and 72 are rotating continuously to rapidly advance the work piece 14 toward the stitching head 12. As seen in FIG. 2 and schematically illustrated in FIG. 3, a photoelectric sensing means 94 is positioned in the work table '13 and functions to sense the leading edge of the box blank or work piece 14 as it advances through the stitching machine. When the photocell detects the presence of the leading edge, it energizes a conventional timer 96 which is set to time out upon the expiration of a predetermined amount of time corresponding to the length of the front flaps of the carton to be constructed from the box blank being stitched by the machine. When the timer 96 is timed out (and the actual overlapping edges 62 and 64 of the work piece 14 are now properly under the stitching head 12), it generates a signal applied to the gate 98 of a semiconductor controlled rectifier 100 which is thereby turned on to complete a circuit comprising voltage source 102, clutch coil 50 of the stitching head 12, the SCR 100, and to ground. Once clutch coil 50 is energized, the stitching head 12 begins the above described stitching cycle.

It should be appreciated, that before the stitching head 12 begins its cycle, the stitch forming and driving means 26 thereof was quite naturally in its upper non-stitching position. Accordingly, the periphery 56 of the shaft end 36 maintains the contacts 54 in their closed condition thereby applying a signal from a voltage source 104 through the contacts 54, through the line 106, to a capacitor-resistor network 107 to apply a pulse to a turn on clutch-tum oft 'brake input terminal 108 of the control means 22. Also, it should be pointed out that a parallel line 110 including a conventional inverting circuit 112 necessarily establishes no signal on the turn on brake-turn oif clutch input terminal 113 of the control means 22.

The pulse applied to the terminal 108 traveled by line 114 and 116 to the gate 118 of a semiconductor controlled rectifier 120 which was thereby turned on to complete a circuit from a six volt source 122 through diode 124, limiting resistor 126, clutch coil 86, and semiconductor controller rectifier 120 to ground. Once the SCR 120 was turned on by the application of the pulse to the gate 118 thereof, it continues to fire such that the clutch coil 86 is constantly energized to attract the armature 90 which in turn engages the clutch 82 and thereby interconnects the motor 18 and the pull roll drive shaft 76. Thus it will be appreciated that even before the stitching head 12 begins its stitching cycle, and before the SCR 100 was ever ignited, the control means 22 had generated the necessary operating signals to have the pull rolls 68 and 72 operating in a continuous mode.

It should also be mentioned at this point, that when the pulse was developed by the capacitor-resistor network 107 to apply a signal to lines 114 and 116, the same signal was simultaneously applied to the line 128 to apply a momentary turn-on signal to the base 130 of transistor 132. As will be explained below, when transistor 132 is momentarily turned on, it will instantaneously establish a circuit from a six volt source 134 through diode 136, through a limiting resistor 138, and through the low impedance transistor 132 to ground. The making of this circuit, necessarily interrupts a circuit which might be made from the six volt source 134, the diode 136, the resistor 138, the brake coil 88, a semiconductor controlled rectifier to be discussed below and ground; thereby guaranteeing the extinguishment of the SCR 140 in the event that it was inadvertently or accidentally conducting. In eiTect, the net result of the pulse having been applied to the turn-on clutch turn-off brake terminal 108 is that the clutch coil 86 remains energized and the possibility that the brake coil 88 could be energized is eliminated.

Before returning to the operation of the stitching head, it will be appreciated that a push button 142 is interposed between a voltage source 144 and a capacitor-resistor network 146 for manually applying a pulse to the line 116 and 128 at start up.

Returning now to the stitching operation, let it be as sumed that the clutch coil 50 has been energized as described previously; the stitching head 12 is operating; and the stitch forming and driving means 26 is about to apply a stitch to the work piece 14 now passing beneath the stitching head 12. At that time, and as noted previously, the cordal fiat 58 of the shaft end 36 will confront the contacts 54 and allow them to revert to their normally open condition thereby effectively providing a not signal on the line 106. This not signal, when inverted at 112 and applied to the capacitor resistive network 111, ends up producing a pulse on lines 148 and 150 to thereby apply a turn on signal to the gate 152 of the SCR 140 and a turn on signal to the base 154 of transistor 156.

When the SCR 140 is turned on, a circuit is completed from the voltage source 134, through the diode 136, through the resistor 138, the brake coil 88, and the SCR 140 to ground. Thus the brake coil 88 has been energized to draw the armature 92 theretoward which in effect turns on the brake 84' to stop the drive shaft 76 and halt the movement of the work piece 14 during the reception of the stitch now being applied by the stitching head 12. Simultaneously, with transistor 156 momentarily turned on, the circuit including the clutch coil 86 and the SCR 120 has been diverted such that the SCR 120 is extinguished; the clutch coil de-energized; and the clutch 82 disengaged.

As described previously, once the stitch is applied and the stitch forming and driving means 26 lifted; the peripheral portion 56 of the shaft end 36 will again close the contacts 54 to initiate the generation of the signals which will turn on the SCR 120 (to initiate clutch engagement) and momentarily energize transistor 132 to extinguish SCR 140 and thereby initiate the disconnection of the brake 84'. Hence the work piece will begin advancing again to await the next brake on clutch off operating signals generated by the control means 22 in response to the operation of the stitching head 12. FIG. 4 shows a typical cycle of operation in which the clutch is on for approximately 60 milliseconds and the brake is on for approximately 40 milliseconds, the six volt level having been dictated by the voltage sources 122 and 134.

When the preset number of stitches have been sensed by contacts 60 and accumulated by a counter 159'; a signal is applied on the line 160 which the capacitor-resistive network 162 converts to a pulse appearing on a line 164 which is applied to the base 166 of a transistor 168 which turns on to thereby momentarily make a low impedance bypass circuit around the SCR 100 which is thereby extinguished. Thus coil 50 is de-energized and the stitching head 12 ceases operation. It should be pointed out that when the stitching head 12 ceases, the stitch forming and driving means 26 will be lifted from the work piece 14 whereby the contacts 54 Will have been closed by the shaft end 36 to generate the necessary pulses for the control means 22 to generate the necessary turn on clutch and turn off brake operating signals whereby the pull rolls will revert to their continuous mode of operation and rapidly eject the work piece out of the rear of the machine 10'.

Turning to FIG. 5, there is illustrated an alternative embodiment of the control means 22 and the manner in which it cooperates with an alternative type of clutch and brake designated 82" and 84" respectively. In this embodiment, the clutch and brake 8-2" and 84" are of the type previously designated purely electrical in the sense that energization of their respective coils 158 and 160 is used to directly establish a flux path through the respective parts of the clutch and brake which draws the laterally moving part thereof into engagement with the stationary part thereof. Such clutches and brakes as illustrated at 82" and 84" in FIG. are conventional and may be purchased on the open market. The distinguishing characteristic thereof is that upon the energization of the respective operating coil thereof, a relatively heavy mass thereof is physically drawn into clutching or braking engagement with the stationary portion thereof. Hence, and as described previously, in the operation of these electrical clutches and brakes, a high voltage surge is initially required to bring about quick engagement while a lesser voltage can be used to maintain the engagement once so established.

The control means 22 of FIG. 5 is provided with circuit means for effectuating this type of operation during an initial portion of the period of time that the clutch 82" or brake 84" is energized during a given cycle of operation. Control means 22 of FIG. 5 includes every one of the elements shown and described in FIG. 3, and corresponding numerals appear in FIG. 5 accordingly. However, the control means of FIG. 5 also includes a volt source 162 which is applied by lines 164 and 166 to two branch circuits. Specifically line 164 is applied to an 'RC network 168, a line 170, and a diode 172 in parallel with the forementioned diode 124. In like manner the line 166 from the 1.20 volt source 162 is applied to an RC circuit 174, and a diode 176 in parallel with the aforementioned diode 136.

In operation, the 120 volt source charges the capacitors 180 and 182 to approximately 120 volts. Thus, when, as described previously, a pulse is applied to the lines 114, 116 and to the gate 118 to turn on the SCR 120; the capacitor 180 will rapidly discharge (the duration depending on the time constant established by the RC network 168) across diode 172, through the operating coil 158 of the electrical clutch 82 and through the SCR 120 to ground. Thus, for an initial portion of the clutch on period, there will be an extremely high voltage spike approaching 120 volts through the operating coil 158 which will generate the necessary high flux to initially move the movable half of the clutch toward the stationary half thereof. After that high spike subsides to a voltage less than 6 volt source 122, the six volt source 122 will continue to apply the lower magnitude clutch holding signal through the coil 158 the SCR 120 and to ground.

In like manner when a brake on signal has been applied to the line 148 and gate 152 to turn on the SCR the capacitor 182 will be initially discharged across the diode 176, the brake operating coil and on to ground through the SCR 140. Once the initial high voltage spikes subsides, the six volt source 134 will continue to apply a brake energizing signal of lower magnitude across the diode 136, to the operating coil 160', the SCR 140, and on to ground. Again, these electrical signals correspond to the fact that for the electrical brake 84" employed, it is first necessary to generate a high voltage spike to rapidly engage the brake, but thereafter, a lesser voltage can be employed to maintain the brake in engagement.

FIG. 6 shows the voltage level which appears across the clutch coil 158 and brake coil 160' respectively during the incremental clutch and brake operation of the stitching machine of the instant invention over a 100 millisecond cycle. Thus, during the first sixty millisecond period when the clutch is to be energized, the RC network 168 is chosen such that the time constant produces the 120 volt spike for approximately 1 millisecond, with the six voltage source maintained on the clutch on for the remaining period. Similarly with the brake, the time constant of the RC network 174 is chosen to generate the 120 volt spike for approximately 1 millisecond with the six bolt source 134 maintaining the brake on for the remaining of the period.

It should be pointed out, that the control means 22 of FIG. 5 is essentially a modified version of the elec tronic circuitry provided by the Warner Electric Clutch and Brake Company of Beloit, Wis. for the operation of an electrical clutch and brake assembly manufactured by this company. The inventor hereof has taken this companys basic control system 22 and the brake and clutch assembly 82 and 84" operated thereby, modified them, and applied them to the incremental advancement of pull rollers of a wire stitching machine operating in conjunction with and dependent upon the stitching cycle of a stitching head associated therewith. In like manner, the control means 22 of FIG. 3 is a modified version of the control means produced by the Warner Electric Clutch and Brake Company of Beloit, Wis.; but, here again, the inventor hereof has modified and combined same in the control of the pull rollers of the wire stitching machine dependent upon and cooperating with the stitching head thereof.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred therefore, that the scope of the invention be limited, not

by the specific disclosure herein, only by the appended claims.

What is claimed is:

1. A stitching machine comprising:

first means for applying fastening means to a workpiece passing thereby;

second means for conveying said Work piece past said first means;

motive means selectively connectable to said second means for the operation thereof;

interconnection means responsive to preselected operating signals for selectively connecting and disconnecting said motive means and said second means; and

control means responsive to operation of said first means for generating said preselected operating signals.

2. The stitching machine of claim 1 wherein said interconnection means includes clutch means for connecting said motive means and said second means; and said control means includes clutch-on circuit means for applying an operating signal to said clutch means for a first preselected period of time.

3. The stitching machine of claim 2 and further including control signal generating means responsive to operation of said first means for generating, a first control signal for said first preselected period of time; and said control means includes enabling circuit means responsive to said first control signal for enabling said clutch-on circuit means.

4. The stitching machine of claim 2. wherein said interr connecting means further includes braking means for positively halting the motion of said second means, and wherein said control means includes brake-on circuit means for applying an operating signal to said braking means for a second preselected period of time which occurs after said first preselected period of time.

5. The stitching machine of claim 4 and further including control signal generating means responsive to operation of said first means for generating a first control signal for said first preselected period of time and a second control signal for said second preselected period of time after the occurrence of said first preselected period of time; and said control means includes first enabling-disabling circuit means responsive to said first control signal for enabling said clutch-on circuit means and disabling said brake-on circuit means.

6. The stitching machine of claim 5 wherein said control means further includes second enabling-disabling circuit means responsive to said second control signal for enabling said brake-on circuit means and disabling said clutch-on circuit means.

7. The stitching machine of claim 2 wherein said clutchon circuit means includes first circuit means for applying an operating signal of a first predetermined magnitude to said clutch means for an initial portion of said first preselected period of time and second circuit means for applying an operating signal of a second predetermined magnitude less than said first preselected magnitude to said clutch means for the remaining portion of said first preselected period of time.

8. The stitching machine of claim 7 wherein said interconnecting means further includes braking means for positively halting the motion of said second means, and wherein said control means includes brake-on circuit means for applying an operating signal to said braking means for a second preselected period of time which occurs after said first preselected period of time; and

wherein said brake-on circuit means includes third circuit means for applying an operating signal of a third predetermined magnitude to said braking means for an initial portion of said second preselected period of time and fourth circuit means for applying an operating signal of a fourth predetermined magnitude less than said third predetermined magnitude to said braking means for the remaining portion of said second preselected period of time.

9. The stitching machine of claim 8 wherein said first and third predetermined magnitudes are equal, and said second and fourth predetermined magnitudes are equal.

10. The stitching machine of claim 8 and further including control signal generating means responsive to operation of said first means for generating a first control signal for said first preselected period of time and a second control signal for said second preselected period of time after the occurrence of said first preselected period of time;

said control means includes first enabling-disabling circuit means responsive to said first control signal for enabling said clutch-on circuit means and disabling said brake-on circuit means; and

wherein said control means further includes second enabling-disabling circuit means responsive to said second control signal for enabling said brake-on circuit means and disabling said clutch-on circuit means.

11. The stitching machine of claim 5 wherein said first means is a stitching head having stitch driving means for driving a stitch into said work piece during a portion of a stitching cycle; said stitching head having operating means for causing said control signal generating means to generate said second control signal when said stitch is being driven into said work piece and for causing said control signal generating means to generate said first control signal at all other times during said stitching cycle; whereby said clutch means will be engaged to advance said work piece whenever said stitching head is not driving a stitch, and said brake means will be engaged to halt said work piece whenever said stitching head is driving a stitch.

12. The stitching machine of claim 11 wherein said control signal generating means includes a voltage source, a turn-on clutch line, an operating turn-on brake line in parallel with said turn on clutch line and normally open contact means in series with the parallel network of said turn-on clutch line and said inverting turn-on brake line for generating said first control signal on said turn-on clutch line when said contacts are closed and for generating said second control signal on said inverting turn-on brake line when said contacts are open.

13. The stitching machine of claim 12 wherein operating means of said stitching head maintains said contact means open when said stitch is being driven into said work piece and closed at all other times in said stitching cycle.

14. The stitching machine of claim 13 wherein said stitching head includes a shaft rotating in synchronism with the operation of said stitch driving means, said shaft having a flat position thereon of predetermined size relative to the remaining circumference of said shaft to correspond to the portion of said stitching cycle when said stitch is being driven in said work piece; said normally 13 open contact means being in preselected location with respect to said shaft to be closed by said remaining portion of said circumference thereof and allowed to revert to its normally open condition by virtue of said flat confronting contact means.

15. The stitching machine of claim 11 wherein said stitching head includes motor means, clutching means selectively operable to interconnect said motor means and said stitch driving means, and stitcher head starting means for energizing said clutching means.

1 6. The stitching machine of claim 15 and further including counter means responsive to operation of said stitching head for accumulating a preselected number of stitches; and stitcher head stopping means responsive to said counter accumulating said preselected number of stitches for de-energizing said clutching means.

17. The stitching machine of claim 16 wherein said control means further includes start-up means for initially enabling said first enabling-disabling cincuit means; whereby when said start up means is operated, said clutch means will be energized; said brake means will be de energized; and said second means will continuously convey said work piece toward said stitching head.

18. The stitching machine of claim 17 wherein said stitcher head starting means includes wonk piece sensing means responsive to said work piece reaching a predetermined position with respect to said stitching head for generating a start-timer control signal; timing means responsive to said start-timer control signal for generating a braking means enabling signal at a preselected time after reception of said start-time control signal; and braking means enabling circuitry responsive to said braking means enabling signal for energizing said braking means.

References Cited UNITED STATES PATENTS 2,785,403 3 1957 Harred 227-7 2,908,011 10/ 1959' Mott 227-7 3,173,592 3/1965 Herbst a 227-7 3,489,328 1/ 1970 Martin 227-7 GRANVILLE Y. CUSTER, JR., Primary Examiner US. Cl. X.R. 227-3, 7 

